In a conventional refrigeration cycle apparatus, when a period of use is extended in a state where clamping of connecting portions of pipes or others is insufficient, refrigerant leakage occurs little by little from a gap in clamped pipes or others in some cases. Moreover, due to damage or the like of pipes, sometimes the refrigerant leakage unexpectedly occurs. Such refrigerant leakage causes a decline in air-conditioning ability or damage to constituting equipment. Moreover, when the refrigerant circuit is excessively filled with refrigerant, pressure transfer of liquid refrigerant is performed for an extended period in a compressor, and thereby failure is caused.
Therefore, from the viewpoint of improving the quality and the maintenance easiness, it is desired that a function of calculating a refrigerant amount charged in the refrigerant circuit to determine excess or shortage of the refrigerant amount is to be provided. In Patent Literature 1, there is suggested a method of measuring operation state amounts at multiple positions in a refrigerant circuit, calculating a refrigerant amount from the measured operation state amounts and comparing thereof with an appropriate refrigerant amount to determine excess or shortage of refrigerant amount.